The present invention refers to a device for removal of trimmings in the production of rolls of web material, in particular rolls of paper, such as toilet paper, kitchen paper, and paper for industrial and other uses. The present invention refers in particular to a device for removal of the head and tail trimmings that are obtained after cutting of rolls of a predetermined length from a long log.
Specific reference will be made herein to rolls of paper, it being understood that the invention can be applied to rolls of any other web material.
In the production of rolls of paper, a web of paper of a certain length is wound on a core, normally of cardboard, to form a log of the desired diameter. The log is then cut to form a plurality of rolls of desired length, according to the use for which the paper is intended. To obtain uniform rolls after cutting, head and tail trimming is done on each log; that is portions of variable length are cut and removed from the respective ends of each log, in which the edges of the various superimposed layers of paper are not aligned with each other.
Removal of these trimmings sometimes takes place manually, by a person set at position where the product leaves the cutting machine. Automatic systems for removal of trimmings are also known to the art, but they have not proved perfectly efficient.
A very widely used system consists in making the cut out paper rolls travel, in the stretch between the cutting station and the packaging station, on conveyor belts between which transverse slits of an appropriate width are formed, into which the head and tail trimmings should fall during the travel. In practice, however, not all the trimmings fall into the slits, causing poor operation of the machine.
An object of the invention is to eliminate the drawbacks of the prior art, ensuring removal of the head and tail trimmings in the production of rolls of paper, irrespective of the size of said trimmings.
Another object of the invention is to provide a device for removal of trimmings that is simple and cheap to make.
These objects are achieved in accordance with the invention with the characteristics listed in appended independent claim 1. Advantageous embodiments of the invention will be apparent from the dependent claims.
The device for removal of trimmings according to the invention has at least one conveyor belt disposed downstream of the cutting area of a log cutting machine. The conveyor belt is engaged on a roller that is horizontally mobile so as to be able to move towards or away from the supporting surface of the cut rolls during the cutting cycle, the trimmings are allowed to fall through the gap formed between the roller and the supporting surface and the cut out rolls are allowed to pass from the supporting surface to the conveyor belt.
Moreover said system allowing the back-up roller for the belt to be moved toward and away from the log-supporting surface also allows the passage of the pushers that push the log as it is fed toward the cutting blade.
The device for removal of trimmings according to the invention fully meets the established objects.
Removal of trimmings according to the invention fully meets the established objects.
Removal of trimmings is extremely precise, thanks to the possibility of horizontal movement of the conveyor belt roller which may be linked to the feeding movement of the logs.
Moreover, the device according to the invention works in the greatest safety, precisely because the back-up roller of the conveyor belt moves away from the roll-supporting surface at the moment when the pusher has to pass, thus avoiding any impact of the pusher with parts of the machine.